Open AccessON THE CONSTITUTION OF THE TERRESTRIAL PLANETS *
Author(s) -
W. H.,
P. M. S.
Publication year - 1949
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1949.tb02951.x
Subject(s) - terrestrial planet , planet , mars exploration program , allowance (engineering) , earth (classical element) , astrobiology , geology , geophysics , physics , materials science , astrophysics , astronomy , mechanical engineering , engineering
Summary It is suggested that the density jump at the boundary of the Earth's core is due to a pressure transition from the molecular to a metallic phase, rather than to the appearance of a new material such as an alloy of iron and nickel. The pressure at the boundary of the core will then be characteristic of the chemical composition of the material, and so may be assumed to be the same for all the terrestrial planets. The mean densities of the terrestrial planets calculated on the basis of this assumption are in good, but not perfect, agreement with the empirical values. The calculated ellipticity of Mars is also satisfactory. If allowance is made for the tendency of the heavier elements to gravitate towards the centre of the Earth, the small discrepancies in the calculated mean densities can be removed.